Secure electrically programmable fuse

Abstract

The present invention provides electrically-programmable fuse structures having radiation inhibitive properties for preventing non-destructive security breaches by radiation imaging techniques such as X-ray imaging, without adversely effecting fuse programmability, and methods of designing the same.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present invention is related to commonly-owned, co-pending U.S. patent application Ser. No. 10 / 904058 entitled PROGRAMMABLE SEMICONDUCTOR DEVICE, the whole contents and disclosure of which is incorporated by reference as if fully set forth herein.BACKGROUND OF THE INVENTION [0002] The present invention relates to programmable semiconductor devices, more particularly, to secure electrically programmable fuses (e-fuses) and methods of manufacturing the same. [0003] E-fuses are widely incorporated in circuit designs for a variety of purposes. For example, e-fuses may be incorporated to replace defective cells or circuits, customize a circuit design for a specific application, or encode data such as electronic chip ID or program code. Conventional e-fuse structures are insecure, and as such, the state of one or more fuses may be ascertained by non-destructive radiation imaging techniques such as X-ray imaging. By non-destructively obser...

AI Technical Summary

Benefits of technology

The present invention provides electrically-programmable fuse structures with radiation inhibiting properties to prevent non-destructive security breaches, such as by X-ray imaging, without adversely affecting fuse programmability. The fuse structures have a radiation inhibitive structure, which may comprise a single or multiple layers, overlying the fuse link and separated from it by at least 0.2 microns of insulating layer. The radiation inhibitive structure has an area of at least that of the fuse link and an X-ray absorbance greater than that of the insulating layer. The method of designing the programmable device involves identifying a fuse link marking layer, storing its center point, length, and width, identifying a metal level, drawing a shape in it, and storing the center point, width, and length of each shape. The technical effect of the invention is to provide a more secure programmable device that prevents unauthorized access and ensures data security.

Problems solved by technology

Metal is prohibited over the fuse link region because metal wiring layers, in particular thick metal wires, diminish the programmability of e-fuse structures because the wiring layers act as parasitic heat sinks.

If the fuse link region is not maintained at a sufficiently elevated temperature during the programming process, the programmability of the fuse may become unreliable.

Metal layers tend to sink heat energy away from the fuse region during programming, thus impacting the reliability of the fuse programming process.

If the fuse is not maintained at a sufficient temperature throughout the programming process, the fuse link region may not be fully programmed (i.e. some of the fuse link region may remain intact, thus forming a quasi-conductive path between the ends of the fuse).

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